1. Field of the Invention
This invention relates to a power generation control apparatus to be used for a motorcar and, more particularly, it relates to a motorcar power generation control apparatus for controlling the power output of the alternator of a motorcar for electrically charging the battery and supplying the electric equipment with power in the motorcar.
2. Prior Art
FIG. 7 of the accompanying drawings is a schematic circuit diagram of a known arrangement for controlling the power output of the alternator of a motorcar. Referring to FIG. 7, there is shown an alternator comprising an AC generator 11, six rectifiers (diodes) 12 and an IC regulator 13, which are housed in a common case.
The AC generator 11 comprises a stator coil 11a having star-connected three-phase windings and a field coil (rotor coil) 11b. As the electric magnet carrying the field coil 11b as part thereof is driven to rotate, the generator produces from its stator coil 11a a three-phase electric current due to the alternating voltage generated in the stator coil 11a and having three phases that are shifted by 120.degree. from each other. The alternating current generated in the stator coil 11a is then subjected to full-wave rectification by means of a full-wave rectifier 12 comprised of a total of six diodes to give rise to a direct current, which is subsequently used to electrically charge a battery 2 by way of a fusible link 3 for protecting the battery and/or feed the electric equipment (not shown) of the motorcar. The electric current for energizing the rotor to make it operate as an electric magnet is fed to the field coil 11b as an excitation current by way of a brush and a slip-ring (not shown) under the control of an IC regulator 13.
If a constant excitation current is fed to the field coil 11b, the electromotive force generated by the AC generator 11 is proportional to the number of revolutions per unit time of the field coil 11b so that the generated voltage has to be regulated. Thus, the IC regulator 13 regulates the excitation current flowing to the field coil 11b in order to maintain the generated voltage to a constant level.
On the other hand, the battery 2 is connected to the alternator 1 by way of a FL 3 for protecting the battery. Each of the loads of the electric equipment of the motorcar is also fed with electricity from the alternator 1 also by way of the FL 3 and the supply line L1 of FIG. 7.
Referring to FIG. 7, the IC regulator 13 is not a relay-based regulator but an IC-based voltage regulator for controlling the output voltage of the AC generator 11 so that it may be housed in the case 1 of the alternator 1. It uses a power transistor for the final regulating stage to raise the intensity of the electric current flowing to the field coil 11b in order to improve the performance of the alternator 1 and also the accuracy of voltage regulation.
When, the ignition switch (not shown) of the motorcar is turned on, the IC regulator 13 operates to cause an excitation current to flow from the battery 2 to the field coil 11b by way of a brush and a slip-ring (not shown) in order to start the AC generator. As the field coil 11b is driven to rotate, an induced electromotive force is generated in the stator coil 11a and the produced electric current is rectified by the rectifier 12 and then electrically charge the battery 2 by way of the FL 3 for protecting the battery. As the voltage generated by the AC generator 11 rises, the voltage at the voltage detection input of the IC regulator 13 connected to the load side terminals of load FLs 41, . . . also rises so that the IC regulator 13 reduces the excitation current flowing to the field coil 11b to maintain the voltage generated by the AC generator 11 to a predetermined constant level.
With the above described known arrangement, wherein the voltage applied to the loads is monitored at the voltage detection input of the IC regulator 13 to control the level of power generation, only the supply voltage is held to a constant level and the intensity of the electric current flowing from the alternator 1 is not controlled while the loads of the electric equipment of the motorcar may be independently turned on and off.
Thus, if the electric charge of the battery 2 has been significantly discharged and the battery 1 shows a reduced voltage, an excessive electric current may flow into the battery 2 in order to electrically recharge it until it is unusually heated to become degraded and/or the FL 3 for protecting the battery is fused, if partly.
As for supplying power to the loads of the electric equipment, the above arrangement modifies the power generated by the alternator 1 by detecting the fall of the voltage that appears when the alternator 1 starts feeding the loads so that there occurs a time lag for the operation of controlling the voltage, leading to significant fluctuations in the supply voltage and, in some cases, functional failures on the part of some of the loads.